Four-component varifocal objective with five fixed and two movable lens members



Nov. 17, 3,540,799

(/B FIXED AND TWO MOVABLE LENS MEMBERS Filed Nov. 8. i968 rl r3 rl r6 r8 r10 r12 r14 r5 r7 r9 rl! r13 r15 d4 d5 d8 dlOd dl4 d5 d7 d9 an dl3 L3 L4 L5 46 LAM,

KARL IIACHEIR Inventor:

Attorney United States Patent Int. Cl.G 02b 15/14, 9/64 US. Cl. 350l84 6 Claims ABSTRACT OF THE DISCLOSURE Varifocal objective with fixed positive front doublet followed by two movable negative singlets and four fixed singlets of respectively positive, positive, negative and positive refractivity, with varifocal ratio of 3:1 and relative aperture of 1:1.9. 1

My present invention relates to a varifocal objective of the type described in my prior Pat. No. 3,274,887, witha fixed positive first component in the form of a biconvex. doublet, a movable negative second component, a movable negative third component and a fixed positive fourth component, the latter consisting of four air-spaced lens members.

The object of my present invention is to provide an objective of this type which, while having the same varifocal range of 3:1 and an aperture ratio of 1:1.9 approaching that of my earlier system, afiords more effective correction of aberrations in all its operating positions.

This object is realized by a choice of lens radii and other parameters substantially as set forth in the several following tables.

The sole figure of the accompanying drawing diagrammatically shows an objective system similar to that of my aforementioned patent, embodying the present improvement.

The system illustrated in the drawing consists of a total of eight lenses L1 to L8 constituting four components I, II, HI and IV. The fixed component I is a positive doublet consisting of biconvex lens L1 (radii r1, r2 and thick ness d1) cemented onto lens L2 (radii r2, r3 and thickness d2) having the shape of a negative meniscus; the internal surface r2 of this component is negatively refracting since the refractive index' of lens L2 is higher than that of lens L1. A variable air space d3 separates the doublet L1/L2 from the second component II which is a nearly planoconcave negative singlet L3 with radii r4, r and thickness d4. The concave surface r5 of lens L3 confronts, across a variable air space d5, a concave surface of smaller radius r6 of the meniscus-shaped negative lens 1.4 which constitutes the third component HI and whose thickness and second radius have been designated d6, r7.

3,540,799 Patented Nov. 17, 1970 d14), the intervening air spaces having been indicated at d9, dll and d13.

The following Tables IA, HA and IIIA list representative values for the parameters r1-rl5 and dl-d14 of lenses L1-L8, their refractive indices n and their Abb numbers v wlth reference to three representative embodiments. In each case the system has a relative aperture of 1:1.9 and a focal length rangmg between 50 and 150 linear units (e.g. millimeters), the radii, thicknesses and separations being given 1n the same units. The back-focal lengths of the three systems are 52.24, 52.37 and 52.52 units, respectively.

' TABLE IA flu 2 r1 =+2s5. 25 L1.... d1 41.10 1. 01772 49. I r2 =-212.00

d3 =108. 22 Variable air space =-740r. II 1.0.... 44 9.80 1.020 11 60.30

a d5 39.62 Variable air space r6 87.01. III L4... as 4.90 1.62041 00.00

d7 20.78 Variable air space r8 =+258. 92 L5.... 118 9.00 1. 52630 51.00

79 =-109. 02 1 d9 63. 73 Airspace r10= +40.56 L0 d10== 12.20 1. 74400 44.30

rl1=-604. 01 IV d11= 12.01 Airspace r12=- 70. 70 L7.... d12= 11.77 1. 74000 28.10

rl3=+ 30. 04 I I113: 3v 92 Air space r14=+ 41. 20 L8.-.. d14= 13. 73 1.07790 55.20

Total d =360.54

TABLE 11s a1 41.16 1. 01772 49. so I r2=211.05

d3 =l08. 26 Variable air space r4=-7a9s.a3 II L3.... 64 9.80 1. 62041 00. 30

- I 38.96 I Variable air space r6=-83.24 III L4.... as 4.90 1.50204 01.20

d7 21.32 Variable air space r8=+258. 79 L5. as 9.80 1.52000 51.00

d9 63.69 Airspace r10=+39.53 L6- a10= 12.25 1.74400 44.00 r11=-604. 01 IV d11= 12.00 Airspace r12=76. 73

d13= 3. 92 Airspace r14=+41.1s L8-. d14= 13. 72 1. 07790 55.20

Total... =360.36

TABLE IIIA 'r1=+321.8 LL.-. d1 41.18 1.61772 49.80 I r2=l95.04

.13 =108.87 Variable air space r4=-7401.96 11......... L3 14 9.80 1.62041 6030 d5 38.88 Variable air space r6=82.2l III L4 d6 4.00 1. 6.2041 60.

d7 20.88 Variable air space r8=+258.92 LIL-.- d8 9.80 1. 52630 51.00

d9 63.73 Air space r10=+50.20 L6.- d10- 12.26 1. 74400 44. 80

111 -60832 IV 1111:- 12.35 Air space rl2=--76.77 L7.-- 1112- 11.77 1. 74080 28. 10

1113:- 7392 Air space r14=+41.20 L8 d14= 13.73 1. 67790 55. 20

Total.... d =360.89

The values of air spaces d3, d5 and d7 given in the preceding tables are for an intermediate overall focal length f=100. The following Tables 18, 11B, and IIIB list their values for three difierent positions of adjustment.

I claim:

1. An optical objective comprising a biconvex doublet L1, L2 constituting a fixed positive first component I, a lens L3 constituting a negative second component H, a lens L4 constituting a negative third component III, and a fixed positive fourth component IV consisting of a plurality of air-spaced lens members L5, L6, L7, L8; said second and third components being movable, relatively to each other and to said first and fourth components, into a first position in which the objective has a relatively small focal length, a second position in which the objec tive has an intermediate focal length, and a third position in which the objective has a relatively large focal length; said lenses L1 to L8 having radii of curvature r1 to 115 and thicknesses and separations d1 to d14 whose numerical values, based upon a value of 100 units for an intermediate overall focal length, together with their refractive indices n and. Abb numbers u are substantially as given in the following table, with the spacings d3, d5 and 1)" given for said second position;

r1= +285.25 L1..- d1 41. 18 1. 61772 49. I r2= 212-06 :13 =108.22 Air space r4= -7401.96 II L3.- d4 9.80 1. 62041 60. 30

d5 39.62 Air space r0=87.01 I11 L4 d0 4.90 1. 62041 60. 30

(17 20.78 Air space r8= +258.92 1.5..-. d8 9.80 1. 52630 51.00

d9 63.73 Air space rl0=+49.56 L6- d10= 12.20 1. 74400 44. 80

. r11==604.61 IV d11= 12.01 Airspace rl2=-76.76 L7.-. d12= 11.77 1. 74080 28. 10

d13= 3.92 Air space r14=+41.20 L8... d14= 13.73 1. 67790 65. 29

Total.... d =360.64

First dposition 3. 69 141. 29 23. 64 Thir position 152. 81 13. 53 2. 28

3. An optical objective comprising a biconvex doublet L1, L2 constituting a fixed positive first component I, a lens L3 constituting a negative second component II, a lens L4 constituting a negative third component III, and a fixed positive fourth component IV consisting of a plurality of air-spaced lens members L5, L6, L7, L8; said second and third components being movable, relatively to each other and to said first and fourth components, into a first position in which the objective has a relatively small focal length, a second position in which the objective has an intermediate focal length, and a third position in which the objective has a relatively large focal length; said lenses L1 to L8 having radii of curvature r1 to r15 and thicknesses and separations d1 to d14 whose numerical values, based upon a value of units for an intermediate overall focal length, together with their refractive indices 11,, and Abb numbers it are substantially as given in the following table, with the spacings d3, d5 and d7 given for said second position:

r1=+285.10 1.1.... d1 41.16 1.61772 49. 80 I r2=211.95

- d3 =108.26 Air space r4=-7398.33 II L3- d4 9.80 1. 62041 60. 30

d5 38.96 Air space r6=83.24 III L4. 116 4-90 1. 50204 61. 20

d7 21.32 Air space r8=+258.79 L5- d8 9-80 1. 52630 51. 00

49 63.69 Air 3 ace f10= +4053 L6- d10= 12.26 1. 74400 44. 80

r11=004.31 IV 4111: 12.00 Air 3 ace r13=+30.62 dl3= 3.92 Air 5 ace Total. d =380.36

First osition 3. 82 140. 52 24. 20 Th1! position 152. 81 12. 91 2. 82

5. An optical objective comprising a biconvex doublet L1, L2 constituting a fixed positive first component I, a lens L3 constituting a negative second component II, a lens L4 constituting a negative third component III, and a fixed positive fourth component IV consisting of a plurality of air-spaced lens members L5, L6, L7, L8; said second and third components being movable, relatively to each other and to said first and fourth components, into a first position in which the objective has a relatively small focal length, a second position in which the objective has an intermediate focal length, and a third position in which the objective has a relatively large focal length; said lenses L1 to L8 having radii of curvature r1 to r and thicknesses and separations d1 to d14 whose numerical values, based upon a value of 100 units for an intermediate overall focal length, together with their refractive indices n and Abb numbers v are substantially as given in the following table, with the spacings d3, d5 and d7 given for said second position:

r1= +321.28 L1..." (11: 41.18 1. 61772 49. 80 I r2= 195.64

d3= 108.87 Air space r4=7401.96 H L3- d4= 9.80 1. 62041 60. 30

r5=+99.17 d6= 38.88 Air space r6= -82.21 III L4. d6= 4.90 1. 62041 60. 30

|i7= 20.88 Air space r8=+258.92 L5- d8= 9.80 1. 52630 51. 00

r9=-160.02 d9 73 A Y r space r1o=+56.29 L6- (110-: 12.26 1. 74400 44.

r1l.= 508.92 IV d11= 12.35 Airspace rl2=76.77

L7.. dlis 11.77 1.74080 28.10

dl3= 3.92 Air pace rl4=+41.20 L8- d14= 13.73 1 67790 55. 20

Total" d =360-89 6. An objective as defined in claim 5 wherein said spaces d3, d5 and d7 have substantially the following values in said first and third positions: 

